Münster-based firm Modulorbeat recently built a one-man sauna on an abandoned steel factory site as part of a year-long festival exploring the economic uncertainty of the region surrounding Bochum, Germany, a former industrial hotbed. The 25-foot-high tower is made from stacked precast concrete units. With three floors and a lounge deck, the compact unit includes a plunge pool, a sauna, and what the firm calls a relaxation room on the top, offering a stunning view of the sky.